Struct EquivalenceClass

pub struct EquivalenceClass { /* private fields */ }

An EquivalenceClass is a set of Arc<dyn PhysicalExpr>s that are known to have the same value for all tuples in a relation. These are generated by equality predicates (e.g. a = b), typically equi-join conditions and equality conditions in filters.

Two EquivalenceClasses are equal if they contains the same expressions in without any ordering.

Implementations

impl EquivalenceClass

pub fn new_empty() -> Self

Create a new empty equivalence class

pub fn new(exprs: Vec<Arc<dyn PhysicalExpr>>) -> Self

pub fn into_vec(self) -> Vec<Arc<dyn PhysicalExpr>>

Return the inner vector of expressions

pub fn push(&mut self, expr: Arc<dyn PhysicalExpr>)

Insert the expression into this class, meaning it is known to be equal to all other expressions in this class

pub fn extend(&mut self, other: Self)

Inserts all the expressions from other into this class

pub fn contains(&self, expr: &Arc<dyn PhysicalExpr>) -> bool

Returns true if this equivalence class contains t expression

pub fn contains_any(&self, other: &Self) -> bool

Returns true if this equivalence class has any entries in common with other

pub fn len(&self) -> usize

return the number of items in this class

pub fn is_empty(&self) -> bool

return true if this class is empty

pub fn iter(&self) -> impl Iterator<Item = &Arc<dyn PhysicalExpr>>

Iterate over all elements in this class, in some arbitrary order

pub fn with_offset(&self, offset: usize) -> Self

Return a new equivalence class that have the specified offset added to each expression (used when schemas are appended such as in joins)

Trait Implementations

impl Clone for EquivalenceClass

fn clone(&self) -> EquivalenceClass

Returns a copy of the value.

fn clone_from(&mut self, source: &Self)

Performs copy-assignment from source.

impl Debug for EquivalenceClass

fn fmt(&self, f: &mut Formatter<'_>) -> Result

Formats the value using the given formatter.

impl Display for EquivalenceClass

fn fmt(&self, f: &mut Formatter<'_>) -> Result

Formats the value using the given formatter.

impl PartialEq for EquivalenceClass

fn eq(&self, other: &Self) -> bool

Returns true if other is equal in the sense of bags (multi-sets), disregarding their orderings.

fn ne(&self, other: &Rhs) -> bool

Tests for !=. The default implementation is almost always sufficient, and should not be overridden without very good reason.